Fuel pump and filter assembly



United States Patent Ofiice 3,278,032 Patented Oct. 11, 1966 3,278,032FUEL PUMP AND FILTER ASSEMBLY Russell F. Smith, Ferguson, Mo., assignorto ACF Industries, Incorporated, New York, N.Y., a corporation of NewJersey Filed Oct. 15, 1965, Ser. No. 505,104 Claims. (Cl. 210-181) Thisinvention relates to a mechanical fuel pump and filter assembly andparticularly to a design, in which the basic considerations are heatdissipation and cost reduction in fabrication.

This application is a continuation-in-part of my copending applicationSerial Number 182,304, filed March 26, 1962, and entitled, Fuel Pump,and now abandoned.

A major problem of fuel pump operation is that of minimizing vapor lockconditions, which occur during the operation of an engine at highambient temperatures and at high speeds. Such vapor lock conditions aredue to fuel vaporizing in the system and also occurring during a soakperiod when the engine stands after a prolonged operation at high speedat a high ambient temperature. The fuel line and fuel pump of the engineare packed closely adjacent to the engine and readily absorb heat fromthe hot engine parts, which condition tends to form vapor in that partof the fuel system. The fuel pump is particularly vulnerable to vapor inthe fuel line and its efiiciency drops rapidly as vapor enters the pump.

Pumps of this type are conventionally made of cast metal housingstructures, which due to their mass and thickness retain heat absorbedfrom the engine and from the hot fuel passing into the pump. It is thusan advantage to utilize a fuel pump that will retain a minimum of heatcarried to it during engine operation. It is also desirable that thepump be able to rapidly conduct heat away from the fuel within the pumpto minimize vapor formation.

Mechanical fuel pumps made of cast metal housings use an excessiveamount of metal alloy and require considerable machining operations. Inconsidering the problem of reducing the cost of fabrication of suchpumps, it has been found that sheet metal construction lends itselfadvantageously for this purpose.

It is therefore one object of the invention to provide a novel pump andfilter combination adapted to overcome the problem of fuel vaporizationand vapor lock in a fuel system due to excessive heating of the fuel.

Another object is to provide a pump-filter unit utilizing primarily thinsheet-metal construction to encourage thereby cooling of the fuel duringthe pumping process.

A still further object of the invention is to provide a unit of the typedescribed including a fuel inlet chamber adapted to circulate fuel forcooling the same during the pumping stroke.

Still another object of the invention is to provide a novel fuel pumphaving a filter element combined therewith for filtering fuel beingpumped.

These and other objects of the invention will be clear to those skilledin the art from the accompanying description made in conjunction withthe drawings.

This invention is directed to a novel design of a mechanical fuel pumpand filter assembly in which heat dissipation is greatly increased bythe use of thin walled metal housing structures and in which costreduction is achieved by the use of shaped sheet metal parts. The fuelfilter chamber is joined integrally with the pump housing structure toform a unitary assembly.

FIGURE 1 is a sectional view in elevation of the novel pump and filterassembly, in accordance with this invention, showing the unit assemblyattached to a portion of an internal combustion engine and communicatedwith the fuel system of the engine schematically represented.

FIGURE 2 is a segmentary view in partial cross section of the fuel pumpof FIGURE 1 taken at to the section of FIGURE 1.

FIGURE 3 is a partial sectional view in elevation of a fuel pump andfilter assembly forming another embodiment of the invention.

FIGURE 4 is a sectional view of the valve structure of the pump ofFIGURES 1-3.

FIGURE 1 discloses the pump and filter assembly of this inventionconnected to the crankcase 10 of an internal combustion engine 12. Thepump portion of the pump and filter assembly includes a pump springhousing 14 attached to a pump housing portion 16. The pump housingportion 16 is a formed cylindrical construction, of iron, or steel, forexample, and having a thickness in the order of 0.030. Pump housing 16has a rim 18 bent up and inwardly over a flange 20 of the spring housing14. The fastening of the rim 18 over flange 20 is done with sufiicientpressure so that the peripheral edge of a circular flexiblerubber-coated fabric pump diaphragm 22 is tightly gripped between rim 18and flange 20. This seals in a fuel-tight manner the diaphragm 22 to rim18. This described method of attaching rim 18 to flange 20 eliminatesthe necessity of using screws through flange 20 which would require alarger flange area. Thus, flange 2G is kept to a minimum size,permitting the positioning of the pump within a smaller space.

The central portion of the pumping diaphragm 22 is made sulficientlyrigid by a pair of back plates 24 and 26 on opposite sides of thediaphragm 22. Backing plates 24 and 26 are tightly fixed together withthe pumping diaphragm 22 in between by spinning over the end 28 of apump rod 30 extending through the several parts. This holds the platesand diaphragm between a shoulder portion 29 abutting the surface ofplates 24 and the spunover head portion 28.

The other end of rod 30 is formed with a nail head 32 which is fittedinto the forked end 34 of an actuating lever 36, which in turn ismounted for pivotal movement on a bearing pin 38 journalled in anextension 40 of the spring housing 14. A flexible noise-suppression wearpad 42 is positioned between the rod head 32 and the forked end 34 ofthe actuating lever '36. A pump driving spring 44 is positioned betweenthe upper surface of backing plate 24 and a support eyelet 46, which isforced by the spring 44 to tightly seal the peripheral edge of a sealingring 48 against a shoulder 50 of the spring housing 14. The actuatingrod 30 passes through the center of sealing ring 48, which permitsreciprocating motion of the rod but fits the rod with suflicienttightness to provide a wiping action. This prevents oil from thecrankcase from penetrating into the portion of housing 14 enclosing thespring 44.

Spring housing 14 is fixed across an opening 52 through the wall of thecrankcase 10 of the engine 12 .and may be attached to the crankcase 10by fastening the housing to studs extending through the flange portion56 of housing 14 from the crankcase 10. The operating lever 36 has anend 61) extending through the opening 52 into the crankcase of engine 12and into contact with an engine driven eccentric cam 62.

A spring 64 is tensioned between a portion of the housing extension 40of the lever arm 36 to hold lever end 60 against cam 62.

A sheet metal plate 51 having a pair of drawn cup portions 53 and 54 ismounted across the housing cup 16, as shown. The rim 55 of plate 51 issealed around its periphery to the lip of housing 16 below the rimportion 18. The sealing of rim 55 may be done in any appropriate manner,such as by brazing or soldering.

During engine operation, the eccentric cam 62 is rotated and causes thepump operating lever 36 to oscillate up and down about pin 38. As viewedin FIGURE 1, the upward motion of the rocker arm end 34 pulls the pumprod 30 upwardly and tensions spring 44. Movement of operating lever 36in a counterclockwise direction permits the spring 44 to press the pumprod and diaphragm 22 downwardly. The space between the plate 51 and thepump diaphragm 22 forms a pumping chamber 25.

A short inlet conduit 68 has one end extending through an aperture inthe wall of the housing 16 and sealed thereto by swedging, brazing orsoldering. A circular plate 70 is welded around its peripheral edge tothe inside surface of housing 1.6 to seal off the portion of housing 16enclosing cups 53 and 54. The space between plates 70 and 51 thus formsan inlet fuel chamber enclosing the cups 53 and 54. Thus, as fuel isintroduced through inlet 68 to the chamber formed between plates 70 and51, the fuel will be circulated to some extent and contacted by the thinwalls of pump housing 16 to foster removal of heat through thecirculated fuel. An aperture 66 in the bottom of cup 53 is for thepassage of fuel from the inlet conduit 68 and inlet chamber 71 into cup53.

An inlet valve assembly 92, is press-fitted or spot welded across theinside of cup 53. The inlet valve unit 92 (FIGURE 4) is formed by asupporting plate 94 having apertures 96 therethrough and supporting avalve stop member 98. A valve washer 180 is positioned between valvestop 98 and the upper surface of the valve support plate 94. The valvewasher 100 extends over the inlet apertures 96 to prevent fuel flowdownwardly (as shown in FIGURE 4) through the apertures 96 from thepumping chamber 25. A light spring 99 between the under surface of stopmember 98 and the upper surface of Washer 100 biases washer in positionon plate 94. An identical outlet valve assembly 102 is fixed across theinside of cup portion 54 to provide an outlet valve to the pumpingchamber 25. The outlet valve assembly consists of similar parts shownfor the inlet valve assembly 92 and includes an outlet valve washer 104.This specific valve structure shown is the subject of my co-pendingapplication Serial Number 169,012, filed January 26, 1962, now PatentNo. 3,198,128.

The open end of the cylindrical housing 16 is formed with a spiralcorrugation shown at 79 to provide a screw threading to which isattached a similarly threaded upper rim 81 of a filter cup 80. The cup80 is also formed of sheet metal and is deep drawn to form a housing fora filter assembly 82. Thus, plate 70 forms with the threaded end ofhousing 16 a housing portion which with the filter support cup 80encloses and supports the filter element 82.

The bottom 72 of cup portion 54 abuts against the plate 70. Cup portion72 is apertured and drawn into a collar 74 which extends through plate70 to form an inlet fuel passage from the interior of cup 54 into thetop of the filter housing.

The filter assembly 82 consists of an outer apertured cylinder 108 made,for example, of fiber board and having a large number of apertures 109therethrough. A metallic cylinder 110 having apertures 111 therethroughis fixed coaxially within the center of the outer cylinder 108. Betweenthe two cylinders is a paper filter element 112 consisting of acontinuous endless strip of filter paper positioned in closely spacedfolds extending btween the two cylinders 108 and 110 and longitudinallywith the axis of cylinders 108 and 110. A pair of end plates 114 and 116hold the two cylinders 108 and 110 in their proper spaced relationshipwith the filter element 112 therebetween. The plates 114 and 116 aresealed to the respective cylinders 108 and 110 so that fuel flowing fromconduit 74 into cup 80 is forced to pass through the apertures 109,through the filter element 112 and into .the hollow center of theapertured cylinder 110. The filter element 82 has a washer 117 fittedtightly within a central aperture of the upper plate 114. This washerfits tightly over the end of an outlet conduit 118 and forms 4 a fueltight seal between the filter element 82 and the conduit 118.

Fuel flowing through the passage 74 into the filter housing flows aroundthe upper end plate 114 of the filter and through the apertured filtercylinder 108, the filter element 112 and through the apertured innerfilter cylinder 110 to fill the space in the center of the filterdefined by the cylinder 110. The outlet conduit 118 has one endextending through the gasket 117 closing the upper end of cylinder 110as described. The other end 120 of the outlet conduit 118 extendsupwardly and outward laterally, as shown in FIGURE 2. Conduit 118extends between the two cup portions 53 and 54, as shown in FIGURE 1, aswell as through the plate 70. The conduit 118 may be welded or brazed atthe points it makes contact with plate and cups 53 and 54. The upper end120 of conduit 118 is sealed by brazing to the wall of the pump housing116. An outlet fitting 122 extends through an aperture in the wall ofhousing 16 and into the end 120 of the conduit, as shown in FIGURE 2.Fitting 122 forms means for attaching a fuel line 124.

The filter assembly 82 is replaceable by merely unscrewing the filtersupporting cup from the threaded end of housing 16 and removing thefilter element 82 from the gasket 117. A new filter unit 82 is slippedonto the gasket 117 and the filter cup 80 is screwed back onto the rimof the support cup 76. A rubber gasket ring 83 is positioned between aflanged portion of housing 16 and a channeled shoulder portion 87 at therim of the supporting cup 80. Upon tightening the cup 80 to the housing16, gasket 83 is tightly pressed between shoulder 85 and rim 87 to forma fuel-tight seal.

In operation, the upward stroke of diaphragm 22, as viewed in FIGURE 1,causes a sub-atmospheric pressure to be formed in the pumping chamber25. This is reflected within the housing cup 53 and inlet chamber 71.Fuel will be pressed by atmospheric pressure from the tank 126 throughan intake line 128 connected to the inlet conduit 68 leading intochamber 71. Fuel is sucked through the inlet valve assembly 92 into thepumping chamber 25.

On the downward stroke of rod 30, spring 44 presses the diaphragm 22downwardly and forces the fuel through the outlet valve assembly 102into the cup portion 54 and through conduit 74 into the filter assembly82. Additional fuel flowing into the filter assembly 82 will fill thefilter housing 80 and force fuel under pressure through the filter 112and into the outlet conduit 118, the outlet fuel line 124 to acarburetor 130.

Fuel lines 124, 128 and carburetor 130 are schematically shown in FIGURE1 with the carburetor mounted on the manifold 132 of engine 12. Theconstruction and operation of carburetor 130 is not a part of thisinvention and thus is not described in detail. However, it may beassumed that the carburetor is of a conventional design and one in whichair is pumped through an air filter 134 to mix with the fuel from line124 within the carburetor 130.

Air and vapor passing through the fuel system to the carburetor becomestrapped in the upper region of the filter cup 80 as the paper filterelement 112, when wet with fuel, prevents the passage of airtherethrough. This trapped air and vapor provides a pulsation dampeningair dome which absorbs the pulsations of the pump. The presence of suchan air dome enclosing an air and vapor accumulation provides an airspace into which fuel is forced under pressure on the pumping stroke andwhich, on the suction stroke, forces the fuel along the line to thecarburetor. The space 115 within the filter eliminates the necessity ofproviding within the pump additional structure for trapping air toprovide such a pulse dampening chamber. An air and vapor accumulationprevents the necessity of the pump on each stroke to move the relativelylarge amount of fuel between the outlet valve structure 102 and thecarburetor mounted at some distance from the pump. Without such adampening or pulse absorbing accumulation of vapor, an undue burden isput upon the pump and diaphragm 22. If the pump assembly is used in anupside-down position from that shown in FIGURE 1, the space 119 at theopposite end of cup 80 will trap air for pump dampening.

Carburetor 130 has an inlet valve which, when the carburetor fuel bowlis filled, closes off the line 124 to the carburetor. Since the enginecontinues to run, the rocker arm 36 will actuate the pumping diaphragmup-. wardly in an intake stroke. The downward stroke of the diaphragmunder the urging of spring 44 will take place only as far as the fuelpressure within the line between the carburetor and fuel pump willpermit. That is, on a downward stroke of diaphragm 22, the inlet valve100 will close off the inlet line 128 and since fuel is also blocked inits flow to the carburetor, fuel pressure within the pumping chamberwill retain the diaphragm in an upward position, and keep the spring 44under tension. The forked end 34 of the lever 36 permits the oscillatingmovement of lever 36 to continue without affecting the pump until thecarburetor inlet valve opens and the fuel pressure in the pump chamberrelieved.

FIGURE 3 of the drawing shows a modification, and an alternateembodiment of the invention adapted for the utilization of a ceramicfilter. Identical structures in FIGURE 3 to those in FIGURE 1 arerepresented by the same numbers, while similar structures arerepresented by the numbers of FIGURE 1 but primed. FIG- URE 3 shows afuel pump in which the pump housing consists of a shortened plate-likeconfiguration 139 having a pair of apertures through the bottom in whichare sealed the lips of two cup-like structures 53' and 54'.

Pump housing 139 forms with the diaphragm 22, the pumping chamber 25 inthe manner described and shown for structure of FIGURES 1 and 2. Inletfitting 68 is sealed through the wall of cup structure 53' with inletvalve assembly 92 fixed between the inlet 68 and the pumping chamber 25.The portion, then, of cup structure 53' below the valve structure 92,forms an inlet chamber 71', as indicated.

Outlet cup 54' has the valve assembly 102 fitted at its upper open end,as indicated, forming an outlet chamber 75 within the remaining portionof cup 54. Outlet passage 74' is formed through the bottom of cup 54'from a flared collar portion fitted through the bottom of a filtersupport structure 140.

This support structure 140 is formed as a downwardly facing cup, thebottom of which is brazed or fastened by other appropriate means to thepump cup portions 53' and 54. The rim of the filter support structure140 is spirally corrugated, as indicated at 79' to receive a threadedupper rim portion 81' of the filter housing structure 142. Thisstructure is formed of sheet metal and drawn into the cup-likeconfiguration, to house and receive a ceramic filter cup 144 having acenter reservoir for holding filtered fuel, in a coaxial nestedrelationship thereto.

The rim of ceramic cup 144 is urged tightly into sealing engagement witha flexible gasket member 150 Which is fitted snuggly around outletconduit 118 and supported by a shallow dish plate structure 148 fixed toconduit 118 and support 140. A compression spring 146 biased between thebottom portions of filter housing 142 and filter cup 144, urges the rimof ceramic cup 144 against sealing gasket 150. A small magnet 152 issupported by a coiled wire in the filtered fuel reservoir, the ends ofwhich wire are embedded in the gasket member 150, as shown to attractand hold any minute ferrous particles which might be carried in thefuel.

The arrangement of structures in FIGURE 3 enables rapid replacement ofthe ceramic filter cup 144 as needed. This is achieved by merelyunscrewing the filter housing 142 from the filter support cup 140,removing the filter, and replacing it with a new filter and thenattaching the housing 142 to the support 140. The rubber gasket 83positioned between portions of the filter housing 142 and the supportstructure 140 provides a fuel-tight seal between these two members.

Operation of the pump and filter structure of 53 is similar to thatdescribed for FIGURES 1 and 2. Fuel from the pumping chamber 25 isforced through the valve structure 102 into the outlet chamber 175. Fuelpasses on into the filter housing 142 and fills the space surroundingthe ceramic filter cup 144. Fuel passing through the filter is forcedupwardly past the magnet 152 and into the outlet conduit 118 from whichit flows into the carburetor in a manner similar to that described forthe structure in FIGURE 1. The purpose of small bar magnet 152 is toprovide a magnetic filtering function which tends to remove magnetic orferrous metallic particles from the fuel as it passes into the conduit118.

The parts of the filter and pump structure shown in FIGURE 3 are againmade entirely of sheet metal with relatively simple fabricatingtechniques and processes. The parts are those provided by drawings andstampings which lend themselves to a much more economical fabrication ofthe parts.

The fuel pump and filter assembly described is one which is made fromeasily formed and fabricated metal parts. These parts are those whichare assembled by soldering, brazing, welding, or any desired and wellknown procedure. The thinness of the metal allows the fuel passingthrough both the pump and the filter portions of the assembly to beexposed to the cooling effect of ambient air. During the operation ofthe motor vehicle air will flow around the engine and the pump assemblyto provide this cooling effect to the fuel in this pump and filterassembly.

Heat transfer through the sheet metal housing 16 and the filter cup ismuch greater than if these parts were formed of cast metal several timesthicker, even though the cast metal were an aluminum alloy having agreater heat conductivity. These pump parts are all. exposed to thecooling effect of ambient air moving over their surfaces due to themovement of the vehicle or the fan 136 of the engine. Thus, the fuelpump is maintained at a lower temperature which minimizes vapor lockconditions. Such conditions exist when the engine is shut off for aperiod of time after a hot run. The heat of the engine builds up and byconduction and radiation to the fuel system heats the fuel in the fuellines and the pump. Upon starting the engine, however, the flow of airpast the pump quickly cools the pump parts to a lower temperature andreduces the vapor conditions in this part of the fuel system.

The thickness of the sheet metal pump and filter structures have beengiven above as being in the order of 0.030. However, the thickness needonly to be sufficient to provide the required structural strength andrigidity for proper pump and filter operation. Such a thickness withsheet steel, for example, may range from 0.010 to 0.0625". Sheet metalof this thickness provides a greater cooling effect and pumps fabricatedin the manner de scribed operate at lower temperatures than those madefrom thicker castings and with the described advantages. It would alsobe Within the scope of this invention to also form the pump springhousing 14 of sheet metal.

From the foregoing description it is clear that the presently describedinvention provides a device exhibiting greater utility both from thepoint of view of economics and also practicality. It is clear, however,to those skilled in the art that the presently described embodiment andthe operation thereof may be altered slightly with-out departing fromthe spirit and scope of the invention as defined in the followingclaims.

I claim:

1. A fuel pump comprising:

(A) a spring housing having a rim at one end defining an opening,

(B) a diaphragm positioned across said opening and having :a peripheraledge fixed to said rim,

(C) an elongated cylindrical pump housing having opposed open and closedends, said open end sealably engaging said rim of said spring housing toform a fuel inlet chamber,

(D) a diaphragm actuating means positioned in said spring housingincluding an elongated rod having one end attached to said diaphragm andhaving the other end engaging an operating lever,

(B) a first thin metal plate fixed across said pump housing and spacedfrom said diaphragm to define a pumping chamber,

(F) a plurality of thin walled cups depending from first thin metalplate into said fuel inlet chamber and opening into said pumpingchamber, check valve means in each of said respective cups forcontrolling the fiow of fuel passing through said pumping chamber,

(G) a thin wall filter housing removeably connected to said pump housingand forming a filter chamber,

(H) a filter disposed in said filter chamber,

(1) at least one of said cups being in fluid communication with saidfuel inlet chamber to receive fuel from the latter,

(I) another of said cups being communicated with said filter chamber forreceiving fuel from the pumping chamber and passing the same to saidfilter compartment,

(K) an inlet conduit communicated with said fuel inlet chamber andadapted to connect to a source of fuel for circulating the latter insaid fuel inlet chamber prior to the introduction of fuel to said atleast one cup,

(L) discharge means communicated with said filter chamber for conductingfuel therefrom.

2. In a fuel pump as defined in claim 1 wherein said housing defines anannular chamber extending co-extensively with said spring housing andhaving a fuel inlet member in communication therewith.

3. In a fuel pump as defined in claim 1 wherein said thin Wall cupcontaining said outlet valve extends longitudinally to said fuel inletchamber.

4. In a fuel pump as defined in claim 1 wherein said respective thinwalled cup members are spaced one from the other and from saidcylindrical pump housing to form passages therebetween to circulateincoming fuel.

5. In a fuel pump as defined in claim 1 wherein discharge meanscommunicated with said filter chamber includes a conduit disposed insaid fuel inlet chamber and transversing a wall of said cylindrical pumphousing for carrying fuel from said filter chamber into heat transferrelation with fuel in said fuel inlet chamber.

References Cited by the Examiner UNITED STATES PATENTS 1,789,611 1/1931Van Ranst 2104l6 2,840,002 6/ 1958 Elder et al.

2,842,267 7/1958 Shire et al. 210--416 2,969,745 1/1961 Johnson et al103-150 2,997,180 8/1961 Loveday.

3,000,467 9/ 1961 Bowers.

3,000,506 9/ 1961 Hultgren.

3,039,485 6/ 1962 Bnohl.

3,076,550 2/1963 Wilhelm 210-438 X 3,082,875 3/1963 Korte 210-443 X3,096,722 7/1963 Fitzgerald et a1 103-150 3,150,601 9/1964 Smith et a1.103l50 3,161,142 12/1964 ReitZ 103150 REUBEN FRIEDMAN, Primary Examiner.

D. M. RIESS, Assistant Examiner.

1. A FUEL PUMP COMPRISING: (A) AN SPRING HOUSING HAVING A RIM AT ONE ENDDEFINING AN OPENING, (B) A DIAPHRAGM POSITIONED ACROSS SAID OPENING ANDHAVING A PERIPHERAL EDGE FIXED TO SAID RIM, (C) AN ELONGATED CYLINDRICALPUMP HOUSING HAVING OPPOSED OPEN AND CLOSED ENDS, SAID OPEN END SEALABLYENGAGING SAID RIM OF SAID SPRING HOUSING TO FORM A FUEL INLET CHAMBER,(D) A DIAPHRAGM ACTUATING MEANS POSITIONED IN SAID SPRING HOUSINGINCLUDING AN ELONGATED ROD HAVING ONE END ATTACHED TO SAID DIAPHRAGM ANDHAVING THE OTHER END ENGAGING AN OPERATING LEVER, (E) A FIRST THIN METALPLATE FIXED ACROSS SAID PUMP HOUSING AND SPACED FROM SAID DIAPHRAGM TODEFINE A PUMPING CHAMBER, (F) A PLURALITY OF THIN WALLED CUPS DEPENDINGFROM FIRST THIN METAL PLATE INTO SAID FUEL INLET CHAMBER AND OPENINGINTO SAID PUMPING CHAMBER, CHECK VALVE MEANS IN EACH OF SAID RESPECTIVECUPS FOR CONTROLLING THE FLOW OF FUEL PASSING THROUGH SAID PUMPINGCHAMBER, (G) A THIN WALL FILTER HOUSING REMOVEABLY CONNECTED TO SAIDPUMP HOUSING AND FORMING A FILTER CHAMBER, (H) A FILTER DISPOSED IN SAIDFILTER CHAMBER, (I) AT LEAST ONE OF SAID CUPS BEING IN FLUIDCOMMUNICATION WITH SAID FUEL INLET CHAMBER TO RECEIVE FUEL FROM THELATTER, (J) ANOTHER OF SAID CUPS BEING COMMUNICATED WITH SAID FILTERCHAMBER FOR RECEIVING FUEL FROM THE PUMPING CHAMBER AND PASSING THE SAMETO SAID FILTER COMPARTMENT, (K) AN INLET CONDUIT COMMUNICATED WITH SAIDFUEL INLET CHAMBER AND ADAPTED TO CONNECT TO A SOURCE OF FUEL FORCIRCULATING THE LATTER IN SAID FUEL INLET CHAMBER PRIOR TO THEINTRODUCTION OF FUEL TO SAID AT LEAST ONE CUP, (L) DISCHARGE MEANSCOMMUNICATED WITH SAID FILTER CHAMBER FOR CONDUCTING FUEL THEREFROM.